diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -446,9 +446,11 @@
 	struct ether_header *eh;
 
 	eh = mtod(*mp, struct ether_header *);
-	if (ntohs(eh->ether_type) == ETHERTYPE_VLAN ||
-	    ntohs(eh->ether_type) == ETHERTYPE_QINQ)
+	if (eh->ether_type == htons(ETHERTYPE_VLAN) ||
+	    eh->ether_type == htons(ETHERTYPE_QINQ)) {
+		(*mp)->m_flags &= ~M_VLANTAG;
 		return (true);
+	}
 
 	qtag.vid = 0;
 	qtag.pcp = pcp;
@@ -1463,6 +1465,7 @@
 			if_printf(ife, "unable to prepend 802.1Q header");
 			return (false);
 		}
+		(*mp)->m_flags &= ~M_VLANTAG;
 	}
 	return (true);
 }